Two's Complement Negation

let toNegative = function(n)
{
    // take the binary complement
    n = ~n;

    // add 1
    n += 1;

    // return final result of -n
    return n
}

let a = parseInt(prompt("Enter an integer"));
let na = toNegative(a);

console.log(`n: ${a}`);
console.log(`n: ${na}`);